The jury in the Angiulo racketeering trial yesterday heard alleged participants - in their tape recorded voices conducting what the government says was a major bookmaking syndicate centered in Boston's North End and manned by 250 operatives.

Justice Department prosecutors introduced into evidence 14 tape recordings of conversations which were obtained through an FBI bug hidden in the headquarters of Gennaro J. Angiulo at 98 Prince St. for four months in 1981.

The tapes were played for the 13 women and five male jurors as the government offered more evidence to substantiate its charge that Angiulo, three brothers and another defendant engaged in a criminal enterprise involving murder, bookmaking, loan-sharking and obstruction of justice.

The principal figure in the case, Gennaro Angiulo, alleged boss of La Cosa Nostra at the time of the FBI's court approved electronic surveillance, is accused of plotting six murders and two attempted murders.

The tapes, supported by videotapes showing alleged organized crime figures entering and leaving the Prince Street apartment house, gave the jury its first example of how some of the accused handled the financial matters of the alleged bookie syndicate and the language they used to conduct their business.

A large portion of the conversations was virtually unintelligible because a radio and television set, and sometimes a citizen's band radio, played in the background in Angiulo's first-floor apartment and office.

But the jurors, unlike the press and public, used government transcripts to assist them in understanding what the participants had to say and to identify the speakers. The transcripts are not evidence - the jurors can consider only what they hear as evidence.

Minutes before copies of the transcripts were to be made public, the US First Circuit Court of Appeals stayed an order by US District Judge David S. Nelson, who had agreed to release copies of the transcripts, tapes and videotapes to the media.

The Court of Appeals held a hearing later in the day on the request by attorney Anthony M. Traini that the documents be withheld from the media until after a jury is selected in the Sept. 9 trial of his client, Richard E. Gambale, 42, of Malden, who is accused with six others of racketeering charges resulting from the Angiulo investigation.

After hearing arguments by Traini, five media lawyers and a government prosecutor, who supported release of the transcripts, the court indicated it will decide by 9 a.m. today whether to uphold Nelson and allow public access to the documents which were viewed by the jury.

Traini's motion was opposed by attorneys for the Globe, The Boston Herald, WHDH, WCVB-TV (Ch.5) and WBUR-FM.

Jane E. Serene, a special Justice Department attorney and one of the prosecutors at the Angiulo trial, urged Judges Hugh H. Bownes and Juan Torruella to uphold Nelson's decision to release the transcripts as they are presented to the jury each day.

With the conclusion of each tape recording yesterday, FBI special agent Arthur R. Everhart, a specialist on the analysis of gambling evidence assigned to the FBI laboratory in Washington, explained the terminology used by individuals in the Angiulo apartment as they talked about the alleged gambling enterprise.

He likened a bookie operation to a large retail store with agents in a role similar to that of sales personnel.

Gennaro Angiulo allegedly was assisted in the enterprise by the other defendants: his brothers, Michele A., 57, and Donato F., 62, both of Medford; Francesco J. Angiulo, 64, of the Prince Street address; and Samuel S. Granito, 78, of Revere, a reputed capo regime, or leader of one faction of the crime family.

On a tape made on Feb. 20, 1981, Francesco Angiulo was overheard talking to one of the reputed Angiulo organization bookies, Joseph (Candy) Cadelino.

Angiulo admonished Cadelino for "cuffing," or extending credit to gamblers.

Cadelino said he was owed $500.

Angiulo: Get the 5 Candy, I want it . . . Let's not start that (expletive). Bring the money in.

Angiulo: Exactly how much does Louie owe you?

Cadelino: $240.

Angiulo: Get the rest and bring it in here . . . I don't let you go two weeks. That's how you got in trouble. Bring it in every week, understand? . . . Candy, there'll be no more cuff . . . Pay every week, Candy, so you won't get in any trouble.

Agent Everhard said some bookies were identified by code numbers, such as one known as "68- B," in the conversations about the day-to-day activities of the Angiulo group.

Everhard explained such terms as a "hit," or winning bet; "commission," or percentage of what a bookie collects; "balance," or what is owed to the operation; "tape," or adding machine paper; and "layoff," or a process in which bookies place bets with other bookies to lower the risk of losing to bettors.